Israeli researchers have discovered that fruit bats seasonally change how they compete with other animals, namely rats, for food.
Under the leadership of Prof. Yossi Yovel of Tel Aviv University’s Department of Zoology, the team of researchers studied the behavior of Egyptian fruit bats (Rousettus aegyptiacus) and black rats (Rattus rattus) over a period of about seven months, between December 2017 and May 2018.
After reviewing hundreds of hours of video, the team found that bats change their feeding behavior throughout the year, becoming more aggressive in springtime.
In the study, published in BMC Biology on October 1, the researchers posit that, since both Egyptian fruit bats and rats eat fruit as a major part of their diet, they are natural competitors for food.
Egyptian fruit bats, which they describe as “generally extremely hesitant,” also see rats as potential predators, which led the team to add this as a hypothesis.
During the observation, the bats and rats were enclosed in a semi-natural habitat at TAU and monitored by cameras, allowing the researchers to observe details of the bat-rat interactions up close.
The team set up the habitat so bats could fly out and forage. Food was provided around sunset every day, attracting nearby rats to the feeding stations and creating competition between the bats and the rats, who both consume the same food.
Observing patterns
After scrutinizing the footage, the researchers noticed a pattern: bats took fewer risks in the winter, avoiding landing near rats, but became braver in the spring, when the number of rats increased.
In the spring, bats were even observed attacking rats for food, which the researchers called “a behavior inconsistent with simple risk-aversion models.”
Still, according to Prof. Yovel, the aggressive tactic “apparently improved their foraging success rate, which rose to 60% in summer compared to only 35% in winter,” supporting one of the hypotheses of the study, namely that “the success of bat foraging when facing predation risk would vary contextually.”
The Egyptian fruit bat is one of Israel’s most common mammals and a key seed disperser, while the black rat is an invasive species found across much of the country, often sharing the same orchards and urban spaces where the two compete for fruit.
According to the researchers, this pattern shows that animals use flexible strategies to balance risk and reward.
“Even in urban or familiar settings, animals face dynamic trade-offs between safety and access to food,” they wrote. Still, relationships aren’t as simple as many think.
As Prof. Yovel put it, “we tend to describe relationships between different species in simplistic terms — either as competition or predation. This study shows how complex such relationships can be and how animals are able to adapt their response strategies to changing circumstances. Because observations in nature are scarce, this complexity is usually difficult to quantify. What we achieved in this study therefore provides another example of the adaptability and intricate lives of wild animals in urban environments.”